Does mom’s flu increases baby’s schizophrenia risk?

Flu and pregnancy had a hot topic since the outbreak of the H1N1 influenza last year. Health authorities lament the fact that the public has been very sceptical of the H1N1 flu vaccine and only very few of the high-risk individuals which included young children and pregnant women were vaccinated.

Researchers at the University of Wisconsin-Madison and the University of North Carolina (UNC) at Chapel Hill investigated the effect of flu infection to the unborn child. They tested the effect of mild flu in pregnant rhesus monkeys and monitored the babies’ development.

12 rhesus macaques were infected with a mild influenza A virus in the early part of its 3^rd trimester, 1 month before the due date. 7 pregnant monkeys who were not infected served as controls. The babies of flu-infected mothers were born healthy and did not differ in terms of weight, gestation length and neuromotor, behavioral and endocrine responses compared on babies of non-infected mothers.

After 1 year, the babies were monitored using magnetic resonance imaging (MRI) brain scans and their behaviour observed. Their results showed that babies exposed to flu infection in utero had smaller brains compared to non-exposed babies. The scans also detected reductions in the amount of gray matter in the cingulate and parietal lobe and of white matter in the parietal lobe. The structural changes observed were very similar to changes observed in humans with schizophrenia.

According to researcher Dr. John Gilmore, professor of psychiatry in the UNC School of Medicine

“The brain changes that we found in the monkey babies are similar to what we typically see in MRI scans of humans with schizophrenia. This suggests that human babies whose mothers had the flu while pregnant may have a greater risk of developing schizophrenia later in life than babies whose mothers did not have the flu. Normally that risk affects about 1 of every 100 births. Studies in humans suggest that for flu-exposed babies, the risk is 2 or 3 per 100 births.”

The study results confirm previous reports from similar studies using rodents. In those studies, flu infection during pregnancy increased the risk for schizophrenia in the rodent offsprings.

According to lead author Sarah J. Short

“This was a relatively mild flu infection, but it had a significant effect on the brains of the babies. While these results aren’t directly applicable to humans, I do think they reinforce the idea, as recommended by the Centers for Disease Control and Prevention, that pregnant women should get flu shots, before they get sick.”